<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>按钮</button>
    <script>

       let btn=  document.querySelector("button")
        btn.addEventListener("click",function(){
            alert("点击了按钮")
        })
         window.addEventListener("resize",function(){
           console.log(window.innerWidth); 
           if(window.innerWidth<900){
             btn.style.display="none"
           }else {
             btn.style.display="block"
           }
         });

    </script>
</body>
</html>